Clearing info with python script
Using the bpy.ops.info operators

Here is a quick little test script.  The info area operators' context are overriden to emulate running in the info area.  


Assumes the info area is screen.areas[0] 
Assumes no prior selection of reports.


Script:

import bpy

context = bpy.context
info = context.screen.areas[0] # do properly
c = context.copy()
c["area"] = info

# test call
bpy.ops.info.select_all_toggle(c)
bpy.ops.info.report_delete(c)


Script version of Is there a way to clear the &quot;info&quot; editor?.  Might need to run all or some twice to make sure all is removed.